HeloName is a String property that represents the identity name of the client establishing a connection to the SMTP server using either the SMTP EHLO or HELO command verbs. HeloName is used when opening a connection to hail the SMTP server. When HeloName contains a blank value, LocalName is used when hailing the SMTP server. 

Set UseEHLO to indicate if client identification is sent using the SMTP EHLO command.

TIdSMTPBase.UseEHLO